Many boats have a folding chair or seat in which the seat back is movable between generally upright and folded positions with respect to a seat bottom. A pair of hinges are often used to connect the folding seat back to the seat bottom and are often located at and extend along the sides of the seat back and the seat bottom. Each hinge of the pair is either identical to or a mirror image of the other hinge. Each of the pair of hinges often includes first and second metal plates that are pivotally connected at their ends. The first metal plate is connected at one side of the seat back with a first end extending therefrom, and the second metal plate is connected to a common side of the seat bottom with a second end extending therefrom. The adjacent extending ends of the metal plates are held together with rivets or pins that provide an axis of rotation for the movable, first metal plate and the seat back with respect to the fixed, second metal plate and the seat bottom. Therefore, being interconnected by the pair of hinges laterally located with respect to the seat, the seat back can be easily moved between the upright and folded positions.
Preferably the hinge is designed such that throughout the extent of motion of the movable hinge member connected to the seat back, no openings are created between the relatively moving hinge members that could pinch the finger or hand of a user. While it is impossible to eliminate the relative motion between the hinge members, it is desirable that during their relative motion, there are no edges on one hinge member that sweep over surfaces of the other hinge member. Such a relative motion between an edge and a surface has the potential of creating a pinch point. Further, such relative motion normally results in the edge reaching a position where it bears against the other hinge member in a supporting relationship to first, control the extent of motion of the seat back with respect to the seat bottom and second, to provide a mechanical support for the seat back when the seat is generally upright and in use. Anytime an edge and a surface have relative motion, the potential for a pinch point exists. Further, if the edge contacts and bears against the other hinge member, a larger pinch point exists.
For purposes of our discussion, an edge of the movable hinge member may move over a surface of the fixed hinge member, or a surface of the movable hinge member may sweep under an edge of the fixed hinge member. Often, such edges are generally parallel to the axis of rotation of the hinge. In addition, other edges which may result in pinching are those that move over a hinge member surface that extends laterally with respect to the seat and perpendicular to the axis of rotation.
Therefore, there is a need for a folding seat hinge, the construction of which does not contain exposed edges on one member that move with respect to a surface of the other member during the hinge motion. Such a hinge construction should also provide a mechanism for limiting the motion of one hinge member with respect to the other hinge member, but without creating pinch points.